1. Field of the Invention
The present invention relates to an ultrasonic motor.
2. Description of the Related Art
At present, ultrasonic motors having smaller sizes, higher torque, longer strokes and higher resolution than electromagnetic motors are coming into wider use.
Incidentally, the ultrasonic motor is a motor which drives a driven body using frictional force generated between an ultrasonic vibrator and the driven body by pressing the ultrasonic vibrator against the driven body. Further, as a press mechanism for pressing the ultrasonic vibrator against the driven body, there has been disclosed, for example, a press mechanism shown in FIG. 9A and FIG. 9B of Jpn. Pat. Appln. KOKAI Publication No. 10-327589.
In other words, disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-327589 is an ultrasonic driver comprising: a vibrator 114 as a periodic vibration member; a projection 113 fixed at the lower part of the vibrator 114; a rail 111aas a movable member of the present invention to be in contact with the projection 113; a rotary member 112 which in contact with the lower surface of the rail 111a and which guides the rail 111a ; a spring member 117 as a joint support pressure member of the present invention to be in contact with the upper surface of the vibrator 114; and rubber sheets 115, 116, 118 disposed between the spring member 117 and the vibrator 114 and between the spring member 117 and a fixed plate 119.
More specifically, the spring member 117 is a leaf spring which is composed of a flat plate portion 117a and a flat plate portion 117b and which is V-shaped in section. Further, in a two-way branch portion 117c branching into the flat plate portion 117a and the flat plate portion 117b, the spring member 117 is fixed at the position of a node of a standing wave in the vibrator 114 via the rubber sheet 115. In the same manner, the flat plate portions 117a, 117b are in contact with one surface of the fixed plate 119 opposite to the vibrator 114 via the rubber sheets 118, 116, respectively.
In the ultrasonic vibrator disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-327589, press force to press the vibrator 114 against the rail 111a is generated using bending reaction force of the spring member 117 according to the configuration described above.